/Engine/Plugins/Importers/USDImporter/Source/USDStage/Public/USDStageActor.h
Always returns the isolated stage, being an invalid stage in case we're not isolating anything.
const [UE::FUsdStage](API\Plugins\UnrealUSDWrapper\UsdWrappers\FUsdStage) & GetIsolatedUsdStage() const